Cleaning apparatus



April 8, 1952 Filed Jan. 31, 1948 E. O. MORTON CLEANING APPARATUS WITNESSES:

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2 SHEETSSHEET l INVENTOR magma- 2 ATTORN EY April 8, 1952 E. o. MORTON 2,592,314

CLEANING APPARATUS Filed Jan. 51, 1948 2 SHEETS-SHEET 2 FILL- ASH DRAIN RI 0 mm spm OFF WITNESSES:

VENTOR Ewea amr I.

ATTORNEY Patented Apr. 8, 1952 CLEANING APPARATUS Eldred 0. Morton, Mansfield, Ohio, assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application January 31, 1948, Serial No. 5,537

10 Claims.

My invention relates to apparatus for cleaning fabrics or the like and has for an object to provide improved apparatus of this kind.

A further object of the invention is to control admission of washing fluid to a washing machine in accordance with the head of water in the machine.

A further object of the invention is to provide improved water admission means for a washing machine having a pump for discharging vitiated water from the machine, wherein the water admission means is rendered inactive in response to a predetermined high head of water in the machine and rendered active in response to operation of the pump regardless of the head of water in the machine.

These and other objects are efiected by my invention as will be apparent from the following descriptionand claims taken in connection with the accompanying drawings, forming a part of this application, in which:

Fig. 1 is a side view of a domestic washing and centrifuging machine constructed and arranged in accordance with my invention, the outer casing for the machine being shown in section.

Fig. 2 is a front view of a portion of the machine showing control knobs for the machine and indicia associated therewith.

Fig. 3 is a diagrammatic vertical sectional view of the machine showing its piping and electrical connections.

Fig. 4 is a sectional view of a pressure switch shown in Figs. 1 and 3.

Fig. 5 is a front view of the water pump of the machine.

Fig. 6 is a section taken along the line VIVI ofFig. 5, and

Fig. '7 is a view partly in section and partly in elevation of a modified form of water pumpghaving a pressure operated switch associated therewith.

It has been proposed heretofore to control admission of a predetermined quantity of water to a washing machine by means of a pressure-actuated mechanism, subjected to the head of water in the machine. The head of water is impressed upon a diaphragm or other movable wall member of the mechanism to close the water admission valve of the washer when a predetermined high head has been attained. The mechanism operates to open the water admission valve or condition it for opening operation when the head of water is reduced to a lower predetermined value. Such control mechanisms operate with a pressure differential so that, if for any reason, it

is desired to admit water to the washer while the head is high, or above the head to which the mechanism responds for opening the water valve, some additional control means must be employed. As an example, it is desirable in some washers, to admit a spray of water to the washer during the draining of vitiated water therefrom and to initiate this spray when the head of water is high or above the head at which the mechanism operates to condition the water valve for opening operation.

' In accordance with the present invention, this operation is effected by a pressure-responsive mechanism operating in conjunction with the wa ter draining pump in such manner that the mechanism conditions the water valve for opening operation when operation of the drain pump is initiated, even though the head of water in the washer at this time may be maximum. The pump is in free and open communication with the tub at all times so that it is flooded when the tub contains any water. It will be understood that the pump impeller is stationary when .Water is' to be retained in the tub. The discharge conduit .of the pump extends above the level of water in the tub to prevent gravitation of water through the pump. When the tub is to be drained, operation of the impeller is initiated. A region of the pump water passages adjacent the center of the impeller is connected to the pressure-responsive device so that, upon starting of the pump, the low pressure obtaining in this region immediately effects operation of the pressure-respone sive device to condition the water valve for opening operation, even though, at this instant, the head of water in the tub may be maximum.

Preferably, a bell having a space for water and air is interposed in the conduit extending between the pump and the pressure-responsive mechanism. The portion of this conduit leading to the pressure-responsive mechanism connects with the air space in the bell. The pressure of the air in this space varies directly with variations in water head. Accordingly, no contaminated water enters said conduit portion or the pressure-responsive device which might, otherwise, clog the conduit or bind the movable member of the pressure-responsive device.

Referring now to Figs. 1 and 3 of the drawings, I have elected to disclose my invention applied to a domestic type clothes washing and centrifuging machine including a casing structure In having a clothes washing and centrifuging unit, generally indicated at II, enclosed therein. The unit ll may be secured to the casing ID in any well understood manner but I prefer to disclose the unit I I resiliently supported within the casing ID by means of a plurality of springs I2 which permit vibration of the unit I I in all modes relative the casing I0. Suitable damping means may be employed for retarding such vibratory movements but they have not been disclosed since they form no part of the present invention.

The washing unit II includes generally a tub I3 having an access opening I4 at the front side thereof which is closed by a suitable hinged,

gasketed door I5. A generally cylindrical basket I6 is disposed within the tub I3 for rotation about a substantially horizontal axis. The basket I6 includes a side wall I! which is perforate substantially throughout its extent, a few of the perforations being indicated at I8. The basket I6 is also provided with a relatively large opening I9 at the front side, thereof which registers with the access opening I4. The basket may also be provided with a plurality of vanes 2| which extend radially inwardly from the side wall I1 and which function to agitate the fabrics in the body of washing water during rotation of the basket, all of which is well understood.

The basket I6 is rotated at a relatively low speed of, for example, 50 revolutions per minute during the washing period and at a relatively high speed of, for example, 500 R. P. M. during the centrifuging period by means of a two-speed mechanism indicated at 22. The latter is adjusted for low or high speed operation by a suitable solenoid 23 which, when energized, effects high speed operation of the basket and, conversely, when deenergized, provides for low speed operation of the basket. As the construction and operation of two-speed mechanisms of the type shown at 22 are well understood in the art, further description of this mechanism is deemed unnecessary. A suitable two-speed mechanism of the type shown at 22 is shown in the H. E. Edwards Patent No. 2,284,047 granted May 26, 1942. The two-speed mechanism 22is driven by a pulley 24, ,belted as shown at 25 to a constant speed electric motor 26, the latter being carried by the tub I3.

' Washing water isv admitted at a proper temperature to the washer through a water supply conduit 2'! which terminates in a nozzle 28 located adjacent or within the access opening I9 of the basket for the spraying of water within the basket I6; The flow of water through the conduit 21 is controlled by a solenoid operated valve generally indicated at 29, which, when energized, is open, and, when deenergized, the valve 29 is closed.

Vitiated water is discharged from the tub I3 by a pump structure generally indicated at 3I and having an' inlet conduit 32 which communicates with a sump 33 formed in the lowermost portion of the tub I3. The discharge conduit of the pump is formed of flexible material such as rubber hose and is indicated at 33a.- The discharge conduit 33a extends upwardly, as shown, to a region above the level of the water in the tub III as the conduit 32, the pump 3| and the portion of the conduit 33a below the level of the water inthe tub are flooded during washing periods or when any water is present in the tub. Further reference to the pump structure is made hereinafter. The pump is driven by the electric motor 26 through a clutch 34 shown, by way of example, as a jaw type clutch. The clutch 34 is actuated by a pivoted arm 35 which is biased by a tension spring 36 to the clutch open position thereof. A solenoid 3'! has the movable armature 38 thereof connected to the pivot lever 35 and, when the solenoid 3'! is energized, the lever 35 is moved to its clutch engaging position against the bias of the spring 36.

The pump 3I shown, by way of example as a centrifugal pump, includes a casing 39 having a pump chamber 4I therein, see Figs. 5 and 6. Within the chamber 4|, an impelleror pump runner 42 is rotatably mounted. The impeller 42 is rotated by a shaft 42a which is connected to one element of the clutch 34. As shown in Figs. 5 and 6, the inlet conduit 32 communicates with an inlet port 43 formed in the central portion of the pump casing and the discharge conduit 33a communicates with a discharge port 44 arranged at the periphery of the pump casing.

For a purpose to be referred to more in detail hereinafter, an air bell indicated generally at 45 is associated with the pump 3I and is preferably carried by the pump. The air bell 45 includes first and second wall members 46 and 41 which'are'spaced apart to define a space 48 for water and air. As best shown in Fig. 6, the peripheries of the walls 46 and 41 are joined as shown at 49. The air bell 45 is secured to the pump 3I and closes the open end of the casing 39 thereof, a gasket 5I being interposed between the air bell and the casing 39. The air bell 45 is secured in place preferably by a removable tie 52, the ends of which engage a flange 53 formed on the pump casing. The central portion of the tie 52 is provided with a screw 54 engaging the air bell 45 and forcing it firmly into engagement with the gasket 5I. With this construction, the tie 52 and the air bell 45 may be readily removed from the pump to gain access to the pumping chamber M or impeller 42 for the cleaning thereof.' The inner wall 41 of the air bell is provided with an orifice 55 at the center thereof which orifice communicates with a low pressure region of the pumping chamber 4I during operation of the impeller 42.

The outer wall 46 of the air bell has a hollow nipple 51 secured therein which communicates with the upper region of the space 48 or the regionthereof occupied by air as described hereinafter. A flexible conduit 58 extends from the nipple 51 and is connected to a pressure operated switch generally indicated at 53 and secured to the outer casing ID of the washer. This switch 59 functions to control operation or energization of the solenoid valve 29 in accordance with the head of water in the tub I5. The switch 53 may be of any well understood construction but preferably includes a housing 6I having a flexible diaphragm 62 mounted therein and defining, with the housing 6I, a pressure compartment 63. The pressure compartment 63 communicates with the flexible conduit 58 as shown so that the pressure in the compartment 63 follows the air pressure prevailing in the space 48 of the air bell 45.

Arranged within the housing 6I is a snapacting switch structure including a frame 62a secured to the housing GI and having a fixed contact 63a insulatedly secured thereto. A movable contact 64 is carried by a flexible contact arm" 65, the latter being insulatedly supported by 'the frame 62a. A U-shape compression spring 66 is arranged between the end of the spring arm 65 and a fixed knife edge 6'! carried by the frame 62 in order to impart snap-action to the switch arm 65 as the spring 66 is moved over center, all'of which is well understood. The switch arm 65 is biased by a compression spring 68 toward its switch closed position at all times and a projection 89 movable with the diaphragm 62 serves to actuate the switch arm 85 in opposition to the bias of spring 68. As shown, a screw H having a handle 12 is employed for vary-- ing the bias of the spring 69 whereby the pressure in the compartment 63 and, therefore, the head of water in the tub at which the contacts 63a and 64 are separated, is varied. The contacts 63a and 64 are electrically connected, as shown in Fig. 4, to terminals 13 insulatedly carried by the housing 8| Energization of the solenoids 23, 29 and 31 and the motor 26 is controlled by a suitable master sequence switch indicated generally at 14. For convenience, I have shown a manually operated switch of the drum type, the drum 15 being shown in development and rotatable in the direction of the arrow. This switch includes a plurality of stationary contact fingers 16 to 80 inclusive and a plurality of movable contact segments 8| to 88 inclusive. The source of power for the apparatus is represented by line conductors L1 and L2 which may, for example, be a conventional residential lighting circuit. As shown,

the contact finger 1B is directly connected to the line conductor L1. The contact finger i1 is connected by a conductor 81 to one terminal of the motor 26, the opposite terminal of which is directly connected to the line conductor L2. The contact finger 18 is connected to a conductor 88 which extends through the pressure operated switch 59 to one terminal of the solenoid valve 29, the opposite terminal of which is connected by a conductor 89 to the opposite line conductor L2. The contact finger 19 connects by means of a conductor 9| with one terminal of the pump solenoid 31, the opposite terminal of which is directly connected to the line conductor L2. The contact finger 88 connects by means of a conductor 92 with one terminal the speed change solenoid 23 the opposite terminal of which is directly connected to the conductor 89 and thence to the line conductor L2. All of the segments 8| to 86, inclusive, are electrically connected together.

Operation 'finger 16, segments 8| and 82, finger TI, conductor 81, motor 26 and line conductor L2. A branch circuit is also energized including the segment '83, which is energized at the potential of the line conductor L1, the finger l8, conductor 88, the closed pressure-responsive switch 59, the solenoid valve 29, conductor 89 and line conductor Lz. Accordingly, the motor 28 rotates the basket H3 at its low washing speed since the solenoid 23 of the speed-changing mechanism '22 -is,, at this time, deenergized. Energization of the solenoid valve 29 initiates the delivery of water to the tub l3. A suitable detergent may be admitted to the tub with the fabrics or it may be later deposited in the tub through a suitable soap opening (not shown).

The water that is admitted to the tubfirst fills the conduit 32, pump chamber 4| and a portion of the discharge conduit 33a. The level .of the water in the conduit 33a corresponds to the level .of water :in the tub l3. Water also flows through the orifice 55 to the space 48 in'the air bell as the water rises in the pump :chamber'l-l Afterthe water in the space 48 has risen above the upper side of the orifice 55, compression of air in the space 48 is effected, which pressure is transmitted to the diaphragm 62 of the pressureresponsive switch 59. When the proper head of water is attained in the tub I3, the air .pressure in the space 48 corresponding to this head will overcome the bias of the spring 68 and separate the contacts 63 and 64 whereupon the solenoid valve 29 is deenergized and further fiow of water to the tub I3 is terminated. The volume of. space 48 is preferably high relative the total volume of the space 48, the tube 58 and the pressure compartment 83 so that the rise of water in the space 48 is limited to an elevation considerably below the nipple 51. Accordingly, washing Water is precluded from entering the tube 58 which. otherwise. might clog the tube.

At this time, the washing operation is carried out by the rotating basket I6 which functions to agitate the clothes in the washing water as is well understood. At the conclusion of the washing operation, the master switch 14 is adjusted 'to'its Drain position whereupon the segment 84 engages the fingers 19 and 18. Engagement of the segment 84 and finger 19 completes a circuit extending from the segment 84, which is now energized at the potential line of line conductor Li to finger l9, conductor 9|, solenoid '31 and line conductor L2. Engagement of the segment 84 and the finger l8 retains the circuit through the solenoid valve 29 which previously was ompleted by the segment 83 and'described heretofore. Energization of the pump solenoid 31 engages the clutch 34 as described and initiates rotation of the pump impeller 4i.' Immediately, a low pressure region in pump chamber 4| adjacent the center of impeller 42 is produced which not only rapidly draws water through the drain conduit 32 but immediately withdraws the small amount of water from the space 48 down to opening 55.

Furthermore, air is also withdrawn from space 48 so that the pressure of the air in the space 48 is relieved. Accordingly, the spring 68 efiects closure of the contacts 63a and 64 of the pressure switch 59. Since the segment 84 and finger '18 are engaged, the solenoid valve 29 is immediately energized and opened for spraying water within the basket [8. It will be understood that water is removed from the tub [3 by the pump 3| at this time at a faster rate than the rate of admission through the nozzle 28. The fabrics being tumbled in the basket are sprayed with fresh clean water as the vitiated water isbeingremoved by the pump. This spray rinse is effective to remove soap and dirt which may adhere to the surfaces of the basket and the fabrics. When all of the vitiated water has been removed from the'tub the master switch is moved to its Fill and rinse position. Accordingly, operation of the pump is stopped by the disengagement of segment 84 and finger l9 and a body of rinse water is admitted to the tub, the apparatus functioning in exactly the same manner as described in connection with the admission of the washing water to the tub. At the conclusion of the rinse period, the master switch 14 is adjusted to its second Drain position whereupon the pump solenoid 31 is energized as described except that its circuit is completed by the segment 85 instead of the segment 84. During the second draining period or when the rinse water is being removed, the spray rinse described heretofore may .not be necessary so that wall IDS.

pressure compartment I I4.

in the second Drain position, the circuit to the solenoid operated-valve is broken at the finger I8 of the master switch I4. At the conclusion of this draining operation, the master switch I4 is adjusted to its Spin position in which the segment 86-and the finger B are engaged to energize the speed change solenoid 23. This circuit extends from the segment 86 which is energized at the potential of conductor L and includes the finger 80, conductor 92, solenoid 23, conductor 89 and the line conductor L2. After a period of centrifuging. themaster switch is adjusted to its "off position wherein all of the electricallytranslating devices are deenergized and the apparatus is rendered inactive. The damp dried fabrics may then be removed from the basket. During inactive periods or when the tub is devoid of water, the pressure switch contacts 63a and 64 are closed by the spring 68 as the compartment 63 is now subjected substantially to atmospheric pressure.

The quantity of water employed for a washing operation may be varied depending upon the weight of clothes to be treated. For a full load, the handle I2 is adjusted to its regular position indicated B in Fig. 2, wherein the bias of the spring- 68 is maximum and, therefore, maximum head of water is obtained in the tub. For lighter loads, the handle- I2 may be adjusted to its medium or low load settings indicated M and L, respectively. When so adjusted the bias of the spring 68 is reduced and lower heads of water are obtained.

- In Figure 7, I have shown a second embodiment of the invention wherein the pump, the air bell structure and the pressure-operated switch are will be referred to by similar reference characters. The air bell structure, indicated generally at 96,

includes an outer cylindrical Wall portion 91 and spaced circular walls 08 and 99 secured at their peripheries to the cylindrical wall portion for defining a space IOI for water and air. As in the prior embodiment, an orifice I02 provides communication between thespace ml and the central region of the pumping chamber 4| which is subjected to low pressure during operation of the impeller 42. The air bell 96 is secured to the pump casing 39 in any suitable manner such as, for example, by means of a plurality of bolts I04.

The pressure-operated switch structure indicated at I05 includes a flanged cylindrical wall I06 secured by means of bolts I0! to the flanged cylindrical wall 91 of the air bell 96. A circular insulating end wall I08 is riveted or otherwise secured to-the side wall I06 and carries stationan! and movable contacts I09 and H0 respecatively. The contact H0 is carried by a Spring 'support III which biases the contact IIO into engagement with contact I09. The movable contact H0 is actuated by a projection IIZ carried by a flexible diaphragm II3 secured at its periphery in any suitable manner to the side As shown, the diaphragm H3 is located adjacent the wall member 98 to define a Communication between the pressure compartment H4 and the space I JI is afforded by an opening H5. As the construction shown in Figure 7 operates in identically the same manner as the embodiment described heretofore, further reference to this construction or its operation is deemed unnecessary. It might be said, however, that the level ing H5 or the pressure compartment H4. non-adjustable switch is shown in the embodiment of Figure 7 but it will be understood that an adjustable switch structure similar to that shown in Figure 4 may be employed. I

The embodiment shown in Figures 1 and 3 is preferable when a. resilient suspension is employed for the washing unit and wherein the pump structure is subject to vibration. In this case, the pressure switch is secured to a fixed or non-vibrating portion of the machine and connected to the pump by the flexible conduit 58. Accordingly, the movable elements of the pressure switch are not subjected to vibration which might, otherwise, disturb the calibration of the pressure switch. When applied to a rigidly mounted pump structure, the unitary arrangement of the pump, air bell and pressure switch, shown in Figure '7, may be employed.

From the foregoing description it will be apparent that I have provided an improved water admission control for a washing machine wherein the quantity of water admitted to the machine is controlled in accordance with the head of water in the machine. The arrangement is such that water may be admitted to the machine for flush rinsing the fabrics or other purposes regardless of the head of water when operation of the fluid discharge pump is effected. Furthermore, my improved control mechanism may be readily adjusted for varying the quantity of water admitted to the machine depending upon the amount of fabrics to be washed.

While I have shown my invention in several forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof.

WhatI claim is:

1. In cleaning apparatus, the combination of a tub for containing a body of cleaning fluid and the material to be cleaned, means for admitting cleaning fluid to the tub, a pump for withdrawing vitiated fluid from the tub and including a pump chamber communicating with the lower portion of the tub, said pump having a port for discharging fluid from said; chamber, an impeller within said chamber for translating fluid through said dischargeport, means for starting and stopping operation of the impeller, a pressure-responsive device for controlling operation of said fluid admitting means and means providing communication between said pressure responsive device and a region of said pump chamber which is subjected to relatively low pressure during operation of the impeller.

2. In washing apparatus, the combination of a tub for containing a body of washing water and the material to be washed, means including a valve for admitting water to the tub, a pump arranged below the tub and including a pump chamber provided with an inlet port communicating with the tub and a fluid discharge port, an impeller within said pump chamber for discharging water through the fluid discharge port, means for starting and stopping operation of the impeller, a pressure actuated device for controlling said water admitting means, an air bell having a space therein for water and'air,

.inlet port thereof and means defining a passage connecting an upper region of said space and said pressure actuated device.

3. In washing apparatus, the combination of a tub for containing a body of washing water and. the material to be cleaned, means including a valve for admitting water to the tub, a pump disposed below the tub and having a chamber formed with an inlet portion communicating with the tub and a fluid discharge port, an impeller disposed within said chamber, means including a pressure responsive member and a control device actuated thereby for-operating said valve, said device being actuated to a first position for closing said valve when said member is subjected to a predetermined high pressure corresponding to the maximum head of water in the tub, said 'devicebeing actuated to a second position for opening the valve when said member is subjected to a predetermined lower pressure, an air bell having a space for water and air, means defining an orificeconnecting said space and the inlet portion of said pump chamber and means defining a passage providing communication between said space and said pressure responsive member.

4. In washing apparatus, the combination of a tub for containing a body of washing water and the material to be cleaned, means including an electrically operated valve for admitting water to the tub, a centrifugal pump for withdrawing Water from the tub and including a pump chamber having an inlet communicating with the tub and a discharge conduit extending above the level of water in the tub to a point of discharge, an impeller within the pump chamber, means for starting and stopping operation of the impeller, a switch controlling said valve, a pressure responsive member for actuating said switch to a first position to close said valve when the pressure responsive member is subjected to a predetermined relatively high pressure corresponding to the maximum head of water in the tub, said switch being actuated to a second position to open the valve when said member is subjected to a predetermined lower pressure, an air bell having a space for Water and air, means providing a passage communicating with said space and a portion of said pump chamber adjacent the inlet thereof and means defining a second passage connecting the upper region of said space and r said pressure responsive member.

5. In washing apparatus, the combination of a tub for containing a body of washing water and the material to be cleaned, means including an electrically operated valve for admitting water to the tub, said valve being open and closed when energized and deenergized, respectively, a centrifugal pump for withdrawing water from the tub and including a pump chamber having an inlet communicating with the tub and a discharge conduit extending above the level of water in the tub to a point of discharge, an impeller within the pump chamber, means for starting and stopping operation of the impeller, a master switch controlling energization of the valve, a second switch in series with said master switch, a pressure responsive member for actuating said second switch, said pressure responsive member actuating the second switch to its open position in response to a predetermined pressure corresponding to the maximum head of water in the tub, said pressure responsive member effecting closing of the switch in response to a lower pre for water and air therein, means providing a actuate the second switch to its open position.

'7. In washing apparatus, the combination of a tub for containing a body of washing water and the material to be cleaned, means including an electrically operated valve for admitting water to the tub. a centrifugal pump disposed below the tub and including a casing having a pump chamber formed therein, an impeller rotatable about an axis within said chamber, said casing having an inlet port communicating with said tub and chamber and an outlet port for convey: ing water from said chamber to a point of discharge, an air bell carried by said casing coaxially thereof and enclosing a space. for water and air, said air bell having an orifice providing communication between said space and a central portion of said pump chamber, a pressure-actuated switch structure carried by said air bell and including a diaphragm spaced from the air bell and defining a pressurecompartment therewith, said air bell having a passage formed in an upper portion thereof providing communication between said space and pressure compartment and a switch actuated by said diaphragm and controlling energization of the electrically operated valve.

8. In washing apparatus, the combination of a fixed frame, a tub for containing a body of washing water and the material to be washed, means including a valve for admitting water to the tub, a pump for removing vitiated water from the tub, resilient means for flexibly supporting the tub and pump as a unit from said frame and permitting vibratory movements of the unit relative the frame, said pump being provided with a pump chamber, an inlet port communicating with the tub and the chamber, an outlet port for conveying water from the chamber and an impeller, means for starting and stopping rotation of the impeller, a pressure-actuated device fixed to the frame for controlling said water admitting means, and means including a flexible conduit for connecting said pressure-actuated device to a region of said pump chamber which is subjected to relatively-low pressure during operation of the impeller.

9. In cleaning apparatus, the combination of a tub structure for containing a body of cleaning liquid and the material to be cleaned, means including a valve for admitting cleaning liquid to the tub structure, pumping means for discharging vitiated liquid from the tub structure, a control mechanism for said valve elevated with respect to the level of the body of cleaning liquid in the tub structure, said control mechanism including a pressure-responsive member and a control device actuated thereby for operating the valve, said device being actuated to a first position for closing the valve when said member is subjected to a predetermined high pressure corresponding to the maximum head of liquid in the tube structure, said device being actuated to a second position for opening the valve when said member is subjected to a predetermined lower pressure corresponding to a lower head of liquid in the tub structure, an air bell arranged at an elevation lower than the level of liquid in the tub structure, said air bell having a space for cleaning liquid and air, means defining a passage connecting said space and a region of said pumping means which is subjected to a relatively low pressure during operation of the pumping means for the flow of liquid therebetween and conduit means connecting an upper region of said space and said pressure-responsive member.

10. In cleaning apparatus, the combination of a tub structure for containing a body of cleaning liquid and the material to be cleaned, means including an electrically operated valve for admitting cleaning liquid to the tub structure, pumping means for discharging vitiated liquid from the tub structure, a pressure-operated switch mechanism for controlling said valve and I elevated with respect to the level of the body of cleaning liquid in the tub structure, said pressure-operated switch mechanism being actuated to a first position for closing the valve in response to a predetermined high pressure corresponding to the maximum head of liquid in the tub struc- 12 ture and to a second position for opening the valve in response to a predetermined lower pressure corresponding to a lower head of liquid in the tub structure, an air bell arranged at an elevation lower than the level of liquid in the tub structure and having an enclosed space for containing cleaning liquid and air, means defining a passage connecting said space and a region of the pumping means, which is subjected to relatively low pressure during operation of the pumping means for the flow of liquid therebetween and conduit means connecting an upper region of said space and said pressure-operated switch mechanism.

ELDRED 0. MORTON.

REFERENCES CITED The following references are of record in the file of this patent:

I UNITED STATES PATENTS Number Name Date 2,302,923 Zimarik Nov. 24, 1942 2,305,154 Gilbert Dec. 15, 1942 

